From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Mon, 8 Mar 2010 23:26:15 +0000 (-0500)
Subject: update test and header rbtree for correct remove use
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=3bc7f395609a073ff46412abeb30bdd5d26dd5c0;p=urcu.git

update test and header rbtree for correct remove use

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/tests/test_urcu_rbtree.c b/tests/test_urcu_rbtree.c
index f707396..bc7a52d 100644
--- a/tests/test_urcu_rbtree.c
+++ b/tests/test_urcu_rbtree.c
@@ -245,6 +245,7 @@ void *thr_writer(void *_count)
 {
 	unsigned long long *count = _count;
 	struct rcu_rbtree_node *node;
+	void *key;
 
 	printf_verbose("thread_begin %s, thread id : %lx, tid %lu\n",
 			"writer", pthread_self(), (unsigned long)gettid());
@@ -261,12 +262,14 @@ void *thr_writer(void *_count)
 	for (;;) {
 		node = rbtree_alloc();
 		rcu_copy_mutex_lock();
-		node->key = (void *)(unsigned long)(rand() % 2048);
+		key = (void *)(unsigned long)(rand() % 2048);
+		node->key = key;
 		rcu_rbtree_insert(&rbtree_root, node, tree_comp, rbtree_alloc,
 				  rbtree_free);
 		if (unlikely(wduration))
 			loop_sleep(wduration);
 
+		node = rcu_rbtree_search(rbtree_root, key, tree_comp);
 		rcu_rbtree_remove(&rbtree_root, node, tree_comp, rbtree_alloc,
 				  rbtree_free);
 		defer_rcu((void (*)(void *))rbtree_free, node);
diff --git a/urcu-rbtree.h b/urcu-rbtree.h
index 8125170..954d493 100644
--- a/urcu-rbtree.h
+++ b/urcu-rbtree.h
@@ -84,8 +84,13 @@ int rcu_rbtree_insert(struct rcu_rbtree_node **root,
 /*
  * Remove node from tree.
  * Must wait for a grace period after removal before performing deletion of the
- * node.
+ * node. Note: it is illegal to re-use the same node pointer passed to "insert"
+ * also to "remove", because it may have been copied and garbage-collected since
+ * the insertion. A "search" for the key in the tree should be done to get
+ * "node".
  * Returns 0 on success. May fail with -ENOMEM.
+ *
+ * The caller is responsible for freeing the node after a grace period.
  */
 int rcu_rbtree_remove(struct rcu_rbtree_node **root,
 		      struct rcu_rbtree_node *node,